[llvm] [ValueTracking] Fix assertion failure when `computeKnownFPClass` returns fcNone (PR #92355)
Yingwei Zheng via llvm-commits
llvm-commits at lists.llvm.org
Thu May 16 01:15:21 PDT 2024
https://github.com/dtcxzyw updated https://github.com/llvm/llvm-project/pull/92355
>From fb9d23f01333d4677899f324464c817bc9bb91ad Mon Sep 17 00:00:00 2001
From: Yingwei Zheng <dtcxzyw2333 at gmail.com>
Date: Thu, 16 May 2024 14:49:22 +0800
Subject: [PATCH 1/3] [ValueTracking] Fix assertion failure when
`computeKnownFPClass` returns fcNone
---
llvm/lib/Analysis/ValueTracking.cpp | 3 +-
.../test/Transforms/InstCombine/known-bits.ll | 40 +++++++++++++++++++
2 files changed, 42 insertions(+), 1 deletion(-)
diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index c8c527a2d4d2f..087cfcc792ee4 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -1126,7 +1126,8 @@ static void computeKnownBitsFromOperator(const Operator *I,
KnownFPClass Result = computeKnownFPClass(V, fcAllFlags, Depth + 1, Q);
FPClassTest FPClasses = Result.KnownFPClasses;
- if (Result.isKnownNever(fcNormal | fcSubnormal | fcNan)) {
+ if (FPClasses != fcNone &&
+ Result.isKnownNever(fcNormal | fcSubnormal | fcNan)) {
Known.Zero.setAllBits();
Known.One.setAllBits();
diff --git a/llvm/test/Transforms/InstCombine/known-bits.ll b/llvm/test/Transforms/InstCombine/known-bits.ll
index 7a38020500517..cb404c0b7f889 100644
--- a/llvm/test/Transforms/InstCombine/known-bits.ll
+++ b/llvm/test/Transforms/InstCombine/known-bits.ll
@@ -1658,5 +1658,45 @@ define i32 @test_qnan_only(float nofpclass(snan sub norm zero inf) %x) {
ret i32 %and
}
+; Make sure that we don't crash when the use of x is unreachable.
+define i64 @pr92084(double %x) {
+; CHECK-LABEL: @pr92084(
+; CHECK-NEXT: [[CMP:%.*]] = fcmp uno double [[X:%.*]], 0.000000e+00
+; CHECK-NEXT: br i1 [[CMP]], label [[IF_THEN1:%.*]], label [[IF_ELSE:%.*]]
+; CHECK: if.then1:
+; CHECK-NEXT: br i1 [[CMP]], label [[IF_ELSE]], label [[IF_THEN2:%.*]]
+; CHECK: if.then2:
+; CHECK-NEXT: [[CAST:%.*]] = bitcast double [[X]] to i64
+; CHECK-NEXT: [[AND:%.*]] = and i64 [[CAST]], 1
+; CHECK-NEXT: ret i64 [[AND]]
+; CHECK: if.else:
+; CHECK-NEXT: ret i64 0
+;
+ %cmp = fcmp uno double %x, 0.000000e+00
+ br i1 %cmp, label %if.then1, label %if.else
+
+if.then1:
+ br i1 %cmp, label %if.else, label %if.then2
+
+if.then2:
+ %cast = bitcast double %x to i64
+ %and = and i64 %cast, 1
+ ret i64 %and
+
+if.else:
+ ret i64 0
+}
+
+define i32 @test_none(float nofpclass(all) %x) {
+; CHECK-LABEL: @test_none(
+; CHECK-NEXT: [[Y:%.*]] = bitcast float [[X:%.*]] to i32
+; CHECK-NEXT: [[AND:%.*]] = and i32 [[Y]], 4194304
+; CHECK-NEXT: ret i32 [[AND]]
+;
+ %y = bitcast float %x to i32
+ %and = and i32 %y, 4194304
+ ret i32 %and
+}
+
declare void @use(i1)
declare void @sink(i8)
>From bdfed3d1ba7a072a07d9df16672bc3b3ec470769 Mon Sep 17 00:00:00 2001
From: Yingwei Zheng <dtcxzyw2333 at gmail.com>
Date: Thu, 16 May 2024 15:35:14 +0800
Subject: [PATCH 2/3] [ValueTracking] Treat fcNone as zero.
---
llvm/lib/Analysis/ValueTracking.cpp | 9 +++++++--
llvm/test/Transforms/InstCombine/known-bits.ll | 8 ++------
2 files changed, 9 insertions(+), 8 deletions(-)
diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index 087cfcc792ee4..39ae8f03be23c 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -1126,8 +1126,13 @@ static void computeKnownBitsFromOperator(const Operator *I,
KnownFPClass Result = computeKnownFPClass(V, fcAllFlags, Depth + 1, Q);
FPClassTest FPClasses = Result.KnownFPClasses;
- if (FPClasses != fcNone &&
- Result.isKnownNever(fcNormal | fcSubnormal | fcNan)) {
+ // Treat it as zero if the use of I is unreachable.
+ if (FPClasses == fcNone) {
+ Known.setAllZero();
+ break;
+ }
+
+ if (Result.isKnownNever(fcNormal | fcSubnormal | fcNan)) {
Known.Zero.setAllBits();
Known.One.setAllBits();
diff --git a/llvm/test/Transforms/InstCombine/known-bits.ll b/llvm/test/Transforms/InstCombine/known-bits.ll
index cb404c0b7f889..895a7e2b42b86 100644
--- a/llvm/test/Transforms/InstCombine/known-bits.ll
+++ b/llvm/test/Transforms/InstCombine/known-bits.ll
@@ -1666,9 +1666,7 @@ define i64 @pr92084(double %x) {
; CHECK: if.then1:
; CHECK-NEXT: br i1 [[CMP]], label [[IF_ELSE]], label [[IF_THEN2:%.*]]
; CHECK: if.then2:
-; CHECK-NEXT: [[CAST:%.*]] = bitcast double [[X]] to i64
-; CHECK-NEXT: [[AND:%.*]] = and i64 [[CAST]], 1
-; CHECK-NEXT: ret i64 [[AND]]
+; CHECK-NEXT: ret i64 0
; CHECK: if.else:
; CHECK-NEXT: ret i64 0
;
@@ -1689,9 +1687,7 @@ if.else:
define i32 @test_none(float nofpclass(all) %x) {
; CHECK-LABEL: @test_none(
-; CHECK-NEXT: [[Y:%.*]] = bitcast float [[X:%.*]] to i32
-; CHECK-NEXT: [[AND:%.*]] = and i32 [[Y]], 4194304
-; CHECK-NEXT: ret i32 [[AND]]
+; CHECK-NEXT: ret i32 0
;
%y = bitcast float %x to i32
%and = and i32 %y, 4194304
>From 3e9762bdd1f7a8e3a54cda4d5ff5994ca25a1cbe Mon Sep 17 00:00:00 2001
From: Yingwei Zheng <dtcxzyw2333 at gmail.com>
Date: Thu, 16 May 2024 16:10:33 +0800
Subject: [PATCH 3/3] [ValueTracking] Address review comments.
---
llvm/lib/Analysis/ValueTracking.cpp | 6 ++----
llvm/test/Transforms/InstCombine/known-bits.ll | 8 ++++++--
2 files changed, 8 insertions(+), 6 deletions(-)
diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index 39ae8f03be23c..e07d14ccbb85c 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -1126,11 +1126,9 @@ static void computeKnownBitsFromOperator(const Operator *I,
KnownFPClass Result = computeKnownFPClass(V, fcAllFlags, Depth + 1, Q);
FPClassTest FPClasses = Result.KnownFPClasses;
- // Treat it as zero if the use of I is unreachable.
- if (FPClasses == fcNone) {
- Known.setAllZero();
+ // TODO: Treat it as zero/poison if the use of I is unreachable.
+ if (FPClasses == fcNone)
break;
- }
if (Result.isKnownNever(fcNormal | fcSubnormal | fcNan)) {
Known.Zero.setAllBits();
diff --git a/llvm/test/Transforms/InstCombine/known-bits.ll b/llvm/test/Transforms/InstCombine/known-bits.ll
index 895a7e2b42b86..cb404c0b7f889 100644
--- a/llvm/test/Transforms/InstCombine/known-bits.ll
+++ b/llvm/test/Transforms/InstCombine/known-bits.ll
@@ -1666,7 +1666,9 @@ define i64 @pr92084(double %x) {
; CHECK: if.then1:
; CHECK-NEXT: br i1 [[CMP]], label [[IF_ELSE]], label [[IF_THEN2:%.*]]
; CHECK: if.then2:
-; CHECK-NEXT: ret i64 0
+; CHECK-NEXT: [[CAST:%.*]] = bitcast double [[X]] to i64
+; CHECK-NEXT: [[AND:%.*]] = and i64 [[CAST]], 1
+; CHECK-NEXT: ret i64 [[AND]]
; CHECK: if.else:
; CHECK-NEXT: ret i64 0
;
@@ -1687,7 +1689,9 @@ if.else:
define i32 @test_none(float nofpclass(all) %x) {
; CHECK-LABEL: @test_none(
-; CHECK-NEXT: ret i32 0
+; CHECK-NEXT: [[Y:%.*]] = bitcast float [[X:%.*]] to i32
+; CHECK-NEXT: [[AND:%.*]] = and i32 [[Y]], 4194304
+; CHECK-NEXT: ret i32 [[AND]]
;
%y = bitcast float %x to i32
%and = and i32 %y, 4194304
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